A whistleblower within the Baltimore Police Department flagged federal investigators to corrupt members of the Gun Trace Task Force years ago — crucial information that later helped launch the racketeering case that took down an entire squad of crooked officers, new documents show.

A newly unsealed affidavit obtained by The Baltimore Sun discloses for the first time that an officer came forward in 2013 with information about Dets. Momodu Gondo and Jemell Rayam, “including that Gondo and Rayam were taking money and stealing drugs during traffic stops while on duty,” Assistant U.S. Attorney Leo J. Wise wrote in the June 2016 document.

It’s not clear what specific information Guinn provided and what actions, if any, were taken in 2013. Rayam already had been investigated — and returned to the streets — in connection with the theft of $11,000 in 2009, which came after a fatal shooting that prompted a lawsuit that the city eventually settled for $100,000. The FBI told The Sun on Monday that the information was not specific enough to go anywhere.

“At that time, investigators completed all logical investigative steps and determined no further federal action was warranted,” said Dave Fitz, a spokesman for the FBI’s Baltimore field office.

But investigators would revisit the tip and contact Guinn for additional information in December 2015, after Gondo and Rayam eventually came to the attention of Harford County sheriff’s deputies and Drug Enforcement Administration agents who were investigating a drug crew led by Antonio Shropshire. The documents show Guinn helped draw a link between Gondo and both Shropshire and another drug dealer whom Guinn knew to be a Gondo associate, Glen Kyle Wells.

“In late 2015, after acquiring newly collaborated information in an ongoing investigation, we again reinitiated contact with this individual to receive more background information,” Fitz said.

The ensuing FBI wiretap case brought down eight officers from the Gun Trace Task Force unit for using illegal tactics to rob people of drugs and cash. Gondo and Rayam both pleaded guilty and cooperated with the government, providing detailed accounts of misconduct that stretched back nearly a decade. They are both awaiting sentencing.

The case has rocked the department — exacerbating community distrust and leading to the disbanding of plainclothes units, the reversal of hundreds of convictions, numerous lawsuits and a commission appointed by the state legislature to investigate the circumstances around the case.

Guinn’s name has been invoked previously in the Gun Trace Task Force case, but in a way that raised questions about his potential complicity. Federal prosecutors brought charges against Gun Trace Task Force Sgt. Wayne Jenkins in connection with a 2010 incident in which drugs were planted on a man named Umar Burley. Though Guinn was part of the team that pursued and arrested Burley, prosecutors did not accuse Guinn of any wrongdoing. He is now a defendant in a lawsuit filed in U.S. District Court by Burley, who claims the officers who tried to stop him wore masks and that he believed they were going to rob him.

Additionally, at the Gun Trace Task Force trial earlier this year, convicted Det. Maurice Ward testified that Jenkins had bumped into Guinn at an in-service training session, and that Guinn told Jenkins that federal investigators had approached Guinn about an investigation into Gondo and Rayam.

This is the status of the nine officers involved in federal corruption case against members of the Baltimore Police Gun Trace Task Force. Members of the squad were found to have stolen thousands of dollars from people using their gun and badge, while bilking taxpayers by earning overtime pay when they weren’t working.

The conversation was portrayed then as a leak, though the revelations about Guinn’s cooperation suggest he also could have been warning Jenkins that officers in his new unit were trouble.

Guinn also was listed among those who spoke with the Independent Review Board looking into the fatal shooting of homicide Det. Sean Suiter, who was killed one day before he was to have testified before a grand jury investigating the Burley incident.

Former Commissioner Kevin Davis previously said he spoke with the FBI about Guinn and was “absolutely confident that there are no administrative sanctions to pursue against” him.

The new documents say the whistleblower first contacted the FBI in 2013, and that the FBI reached out to him again in December 2015 as the nascent racketeering case was beginning to come into focus. Shropshire’s drug crew was under scrutiny, but the investigators then had come across questions related to Gondo.

“Investigators believe Officer-1’s motivation to come forward with the information was based on his employment obligation to report suspicions of inappropriate behavior and further investigators believes [sic] Officer-1 to be reliable,” the affidavit says.

The officer told the FBI that he was familiar with Shropshire from his work investigating drug dealers. He recalled being at a restaurant when he spotted Gondo and Shropshire together. Gondo introduced Shropshire to the officer as his “brother,” leading to a “moment of tension based on Officer-1’s knowledge of Shropshire.”

City Solicitor Andre Davis told members of the Commission to Restore Trust in Policing on Tuesday...

Gondo assured Shropshire that the officer was “cool.”

“Officer-1 was upset that Gondo vouched for Officer-1 to Shropshire in that way,” Wise wrote. The officer provided two telephone numbers for Gondo, whom he said he had not had any contact with since 2013. He also told investigators that Gondo partied with Shropshire, frequenting clubs in Washington and traveling to Las Vegas, and that he believed Gondo and Shropshire grew up together, and that Gondo and another drug dealer, Wells, were also friends.

Investigators in the Gun Trace Task Force case repeatedly refer to Guinn’s information in the affidavits to establish their probable cause to believe that Gondo has relationships with drug dealers.

Questions have continued to linger about what information Baltimore police and other authorities had on the corrupt officers, several of whom have since admitted to years of misconduct and robberies. A commission appointed by the legislature and Gov. Larry Hogan is conducting an independent investigation of the case, while Baltimore police have said that under state law they can’t comment on discipline and internal investigations.

The FBI obtained a wiretap on Gondo’s phone, revealing that the gun unit was using GPS trackers without warrants that the officers had personally purchased. As they continued to listen in, they learned that the unit was fabricating probable cause, conducting illegal searches and stealing money and drugs from people they were pursuing.

After being charged with racketeering and drug conspiracy crimes, Gondo cooperated with federal prosecutors, providing a stunning window into the officers’ crimes.